L2: White Wine Components and Acids Flashcards
Name the four acids found in wine
Tartaric*
Citric
Malic
Lactic
Describe Citric Acid
Lends a citrus flavor
Only trace amounts of this acid (0.04-0.7 grams per liter) are found in wine. This acid is easily converted into lactic acid by wine microorganisms. It is the primary acid used to increase the acidity in a wine after harvest (“acidification”, discussed in Lesson 6).
During the course of winemaking other acids can play a significant role, such as acetic, butyric, ascorbic, succinic and sulfurous acids. Most of the acids involved are fixed acids with the notable exception of acetic acid, mostly found in vinegar, which is volatile and can contribute to the wine fault known as volatile acidity.
Describe Malic Acid
Apple / Orchard Fruit Flavors
Malic acid can be found in many types of fruit, such as apples and pears. Flavorwise, it tastes almost exactly like a sour green apple. Unlike tartaric acid, malic acid is considered biologically fragile and is easily metabolized by different strains of wine bacteria. It is usually present at a level of 1-4 grams per liter of juice. Malic acid confers a tart taste to wine, although the amount decreases with increasing fruit ripeness. When all malic acid is metabolized, the grape becomes overripe.
Describe Tartaric Acid
Most important acid in wine. Unique antibacterial properties.
Most prevelant acid in wine. “Defines wine”
Half life of 10k years
Other than grapes, there are few fruits that contain significant amounts of tartaric acid. It accounts for anywhere from a half to two-thirds of the acid content of ripe grapes and is the strongest of the grape acids. It is responsible for much of what we perceive as tartness in wine. It contributes to both biological stability and longevity due to its resistance to decomposition.
Once fermentation is completed, the quantity of tartaric acid slowly decreases in small amounts. This results in salt-like crystals on the cork or at the bottom of the glass. (See “Sight” in Lesson One for a discussion of tartrates.) Most winemakers will take steps to ensure that tartrates do not remain in the bottled wine. This process is called “cold stabilization”: first the wine is chilled so that crystals form, then it is filtered before bottling.
Describe Lactic Acid
Through malo-lactic fermentation. Bacteria ‘eat’ malic acid and produce lactic acid.
“Softer” acid. Buttery odor / texture.
Think of lactic acid as the main acid in milk. Lactic acid is formed mostly by bacteria in the conversion process of malolactic fermentation (“MLF”). The process breaks down malic acid, resulting in the softer, buttery-smelling lactic acid. MLF can also add flavour and complexity to wines. Wines that have undergone this “softening” process usually have many more times tartaric than malic acid. They are also more stable.
Some white wines, such as Chardonnay, undergo malolactic fermentation as a matter of course. All red wines undergo malolactic fermentation. Care must be taken that the amount of buttery-smelling diacetyl produced by this process is not excessive, which can be unpleasant in the finished wine.
What happens to acids and sugars as grapes ripen
Acids decrease
Sugars incresae
Harvested early = “higher acid, underripe fruits”
Harvest on time = “Fresh” = medium acid
Harvested late = “overripe”, “jammy”, “cooked” - lower acid
How do you describe medium levels of acid?
Fresh
Examples of high acid red flavors:
Red:
Cranberry
Pomegranate
Under ripe strawberry
What compound creates the unique aroma in Suavignon Blanc
Methopyrazine
Grassy, Green Pepper, Jalapeno
Describe Reisling (ABT, Fingerprint, Flavors)
Acid: High
Body: Low
Fingerprint: Petrol
Other: Citrus, Tree Fruit, Minerality, Floral
Riesling is a very aromatic and expressive grape variety, lending impressions of fresh flowers, especially honeysuckle. Riesling’s aromas and flavors are often compared to orchard fruits like apple, peach, and apricot, but can turn to lemon-lime if grown in a cool climate. Riesling is a light-bodied and highly acidic wine. It is often described as tasting clean, racy and bright. Riesling can take on more complex aromas which can include an aromatic expression of petrol, diesel or linalool.
Describe Sauvignon Blanc (ABT, Fingerprint, Flavors)
Acid: Medium to High
Body: Low to Medium
Fingerprint: Green Pepper / Grass (methopyrazine)
Other: Grapefruit, Minerality
The varietal identity of Sauvignon Blanc is similar to cut grass or bell-pepper. New Zealanders liken it to “gooseberry.” The level of pyrazine influences whether its varietal character is mild or intense.
Describe Chardonnay (ABT, Fingerprint, Flavors)
Acid: Low to Medium
Body: Medium to High
Fingerprint: None (Butter if Malo)
Other: Apples, Pear, Tropical Fruit, Oak (optional)
Chardonnay might smell like apples, lemons, peaches or tropical fruits. Its delicacy is such that even a small percentage of another varietal blended into a Chardonnay will often completely dominate its aroma and flavor. Oak takes over Chardonnay if the wine is fermented or aged in new barrels, or for too long in seasoned ones.
In spite of any variance in style, Chardonnay is unmistakable in the mouth because of its balance, medium to full body, and overall smoothness. Its most defining characteristic comes from malolactic fermentation, lending a soft, buttery flavor profile. Chardonnay’s intrinsic blank canvas quality allows its flavors to be dramatically affected by differences in soil, climate, and vineyard practices.
When Malic acid has been metabolized, what happens to the acid profile
Wine tastes more ripe – less tart, underripe flavors
Which family of compounds is responsible for the petrol odors in reisling?
Terpenes
TERPENES
Terpenes constitute the largest group of organic compounds in grapes. Noteworthy examples include linalool, limonene, and citronelle. These are responsible either singly, or in combination, for generic floral aromas like rose and lavender. They also contribute to fruit aromas, such as orange peel in wines from the Muscat family of grapes; lemon in many Mediterranean white wines; lime in German Riesling; New Zealand Sauvignon Blanc’s under-ripe grapefruit; and the melon common in Chardonnay from California and Australia. It also can be found in the mushroomy aromatics of wines from Italy’s Piedmont. Other terpenes include methyl keton (acacia flowers); damascanone (roses); licorice in red wines; and a combination of terpenes forming the petrol and diesel fuel in Riesling.
Which family of compounds is responsible for the peachy flavors in riesling, vigonier, and new world chardonnay?
Aldehydes
ALDEHYDES
These are formed by microbial activity and by oxidation during the aging process. We sense aldehydes as tart, under-ripe red cherries in Pinot Noir and darker cherries in Sangiovese, Cabernet, and Syrah. Peachy flavors in Viognier, Riesling, and New World Chardonnay are the result of piperonal. In older, more oxidized wine, aldehydes impart a nutty characteristic.
